/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffect.h
Adds a new modified attribute struct, will always add so check to see if it exists first
[FGameplayEffectModifiedAttribute](API\Plugins\GameplayAbilities\FGameplayEffectModifiedAttribute) * AddModifiedAttribute ( const [FGameplayAttribute](API\Plugins\GameplayAbilities\FGameplayAttribute) & Attribute )